Methods and materials

For the image processing, the source code (generic C, uses linux/X11 for display) has been made available
despite the fact it was only ever intended as a throwaway hack - see the README file for further
details.

The software expects the input images to be in RAW format; that is, no header, just a stream of bytes,
either 1 per pixel for greyscale (imdiff.c) or 3 per pixel for RGB (apod.c). You'll have to make sure
the dimensions set in the source code agree with the image you're using. The way I prepared images was,
roughly:-